A series of processes for forming a resist pattern on a substrate, such as a semiconductor wafer (hereinafter referred to simply as “wafer”) is carried out by a resist pattern forming system including, in combination, a coating and developing system for applying a liquid resist to the surface of a substrate to form a resist film and developing the exposed resist film, and an exposure system.
A coating and developing system disclosed in, for example, Patent document 1 includes a film forming block including coating modules for processing a wafer by a coating process before the wafer is subjected to an exposure process, and a developing block including developing modules for processing the wafer processed by the exposure process by a developing process. The coating block and the developing block are superposed. Each of the coating block and the developing block has one end connected to a loading/unloading port and the other end connected to an exposure system by an interface block. This known coating and developing system performs the coating process and the developing process separately to enhance throughput.
The resolution of the exposure system has been improved in recent years. According to the present status of art, the exposure process is capable of achieving a resolution on the order of several tens nanometers by using, for example, an ArF light source (argon fluoride light source). However, the position of a point where light is to be focused is sensitively affected by, for example, the expansion or contraction of a holding member included in an optical system due to a slight change in the environmental condition caused by changes in the atmospheric pressure and weather. The quality of a resist pattern is greatly dependent on such a change of the position of a point where light is to be focused. Therefore, the exposure system needs to be inspected and adjusted frequently, for example, in one day.
There is a tendency to lower the cleanliness of a clean room to reduce the operating cost of a plant. Therefore, the inspection of the exposure system is performed by carrying a test wafer from the carrier handling block of the coating and developing system into the exposure system by the carrying system of the processing block without opening the maintenance door of the exposure system. The coating and developing system mentioned in Patent document 1 needs to use either the coating block or the developing block to carry the test wafer to the exposure system. Therefore, the periodic or occasional inspection and adjustment of the exposure system cannot be done if the coating block and the developing block are under maintenance work or are out of order. Thus the test wafer is carried into the exposure system for the inspection and adjustment of the exposure system after the completion of maintenance work for the coating block and the developing block. Consequently, wafers cannot be processed immediately after the completion of maintenance work for the coating and the developing block, which is one of causes that reduce the throughput of the coating and developing system.
It is an important theme to start up a newly installed semiconductor device fabricating line in a short time. The configuration of the system disclosed in Patent document 1 does not permit the adjustment of the exposure system unless the adjustment of the carrying system of the coating block or the developing block is completed. Since the exposure system has many adjustment items requiring fine adjustment, the adjustment of the exposure system takes a long time. Consequently, it is difficult to reduce time necessary before starting up the semiconductor device fabricating line.
Patent document 1: Jpn. Pat. No. 3337677